The present invention relates generally to a superwide-angle lens optical system, and more particularly to a superwide-angle lens optical system comprising a relay lens system as well as an imaging unit and a display unit, each comprising the same.
So far, a superwide-angle lens system has been used in various applications in the form of such fish-eye lenses as set forth in the following patent publications 1, 2 and 3.
Patent Publication 1
JP(A)62-36622
Patent Publication 2
JP(A)2002-72085
Patent Publication 3
JP(A)5-273459
However, when there is provided a back focus enough to receive an optical path-bending member such a quick return mirror used with single-lens reflect cameras, etc. and various filters, etc., a problem arises; the back focus becomes long with respect to the focal lengths of lenses, and so the diameter of an object-side lens becomes too large. As the image circle of an image pickup plane increases, another problem arises; the diameter of the object-side lens becomes too large. In addition, such prior art lens systems are not fit for improvements in the degree of flexibility in optical system layouts by incorporating a plurality of optical path-bending members, or layouts wherein a relatively wide air space is allowed for in a lens group to receive a plurality of optical systems efficiently.